The present invention relates to a one-hand openable and closable umbrella which can be opened and closed with one hand.
FIG. 9 shows a conventional umbrella of this kind which has previously been proposed by one of the inventors of this application (see Japanese Patent Publication No. 41201/86) and has a double shaft composed of an inner shaft 1a and an outer shaft 1b which are smoothly slidable relative to each other. A required number (usually eight) of main ribs 2 are pivotally secured at one end to the top of the inner shaft 1a so that they extend radially thereof at predetermined angular intervals (360.degree./8=45.degree. when the number of main ribs 2 is eight). A required number (equal to the number of main ribs, that is, eight) of auxiliary ribs 4 are pivotally secured at one end to the top of the outer shaft 1b so that they extend radially thereof at predetermined angular intervals (45.degree. when the number of auxiliary ribs is eight), and as indicated by 2a, they pivotally support at the other end the main ribs 2 near the positions where the main ribs 2 are secured to the inner shaft 1a. A handle 6a is mounted on the lower end portion of the outer shaft 1b and an auxiliary handle 6b is attached to the lower end of the inner shaft 1a. A coiled spring 5 is mounted on the upper and portion of the inner shaft 1a so that it provides a force between the outer shaft 1b and the inner shaft 1a in a direction in which to cause the upper end portion of the outer shaft 1b to approach the upper end portion of the inner shaft 1a. On the handle 6a there is provided a control button 7a as a releasable locking mechanism for temporarily inhibiting the relative sliding movement of the outer shaft 1b and the inner shaft 1a. When the control button 7a is depressed, the temporary inhibition of the relative sliding movement of the shafts is released. The relative sliding movement can be temporarily inhibited again in a state in which the positional relationship between the outer shaft 1b and the inner shaft 1a has been changed while the handle 6a has been brought down to the vicinity of the auxiliary handle 6b, closing the main ribs 2 (a first state).
When the umbrella is held in its folded state, the handle 6a is normally in contact with the auxiliary handle 6b. When depressing the control button 7a with one finger of the hand holding the handle 6a so as to open the umbrella, the inner shaft 1a is slid down relative to the outer shaft 1b by the elastic force of the spring 5, by which the auxiliary ribs 4 act to spread out the main ribs 2, opening the umbrella. The umbrella can be used in such a state, but when it is desirable to fix the main ribs at their fully opened position on a windy day, for example, the auxiliary handle 6b mounted on the lower end portion of the inner shaft la is pulled down away from the handle 6a with a finger of the hand holding the umbrella, by which the umbrella is put in such a second state as shown in FIG. 5, in which the outer shaft 1b and the inner shaft 1a are locked to each other.
In the case of closing the umbrella, the control button 7a is depressed with a finger of the hand holding the handle 6a, the tip of the outer shaft 1b is slightly pulled away from the tip of the inner shaft 1a under the action of the coiled spring 5 and the auxiliary ribs 4 are closed, by which the main ribs 2 are slightly moved in the direction to be closed. The coiled spring 5 is not so stiff, as mentioned previously; so that, by lightly pulling the handle 6a toward the auxiliary handle 6b which is pressed against an user's body, for example, the main ribs, slightly closed as mentioned above, are fully closed with ease, and hence the umbrella is folded up with the outer shaft 1b and the inner shaft 1a locked to each other.
In this prior art example, however, the positions 2a of the auxiliary ribs 4 supporting the main ribs 2 are relatively close to the inner shaft 1a (about 7 to 10 cm) when the umbrella is open, and consequently, in the case where the wind is high, the main ribs 2 and cloth spread thereon may become slack, making the umbrella unstable in its opened state.
By locating the positions 2a away from the center of the umbrella, the main ribs 2 can be made stable in its opened state, but the auxiliary handle 6b further extends downwardly of the handle 6a accordingly, making the umbrella unhandy to use and unshapely.
It is an umbrella shown in FIG. 10 to solve the above-mentioned defects (see Japanese Utility Model Public Disclosure No. 169116/89). This umbrella is provided with lateral auxiliary ribs 4a in addition to the auxiliary ribs 4 in the prior art example shown in FIG. 9. The outer ends of the lateral auxiliary ribs 4a pivotally support the main ribs substantially centrally thereof as indicated by reference, numeral 2b, and the inner ends are pivotally secured to the inner shaft 1a as indicated by reference numeral 4b. Furthermore, the lateral auxiliary ribs 4a are each pivotally supported by the upper end of the corresponding auxiliary rib 4 at a position of about 1/3 of the entire length of the rib 4a from the inner end thereof as indicated by reference numeral 4c. With such an arrangement, the lateral auxiliary ribs 4a are substantially horizontal as shown when the main ribs 4 are fully opened. The spring 5 is shown to be in its contracted state, and its expanding elastic force is utilized for opening and closing the umbrella. The upper end of the spring 5 is fixed to the inside of a ferrule mounting member 8.
When the control button 7a is depressed to open the umbrella, the spring 5 is still contracted but, by its expanding elastic force, the main ribs 2 starts to be spread out. At the time point when the main ribs 2 reach their fully opened position as depicted in FIG. 10, that is, when the lateral auxiliary ribs 4a assume their substantially horizontal position, the elastic force of the spring 5 acts effectively, by which the main ribs 2 are pressed against the cloth tied thereto. At this time, the relative sliding movement of the inner shaft 1a and the outer shaft 1b is inhibited by a stopper 9b.
A hole for locking the umbrella in its opened state needs only to be provided, if necessary. Where the umbrella is manufactured for use under special conditions, for example as a golf umbrella, the provision of such a hole is the inner shaft 1a will make the umbrella more stable when it is put up.
The prior art examples described above both have a construction in which the inner and outer shafts are engaged with each other and they have an upper nest and a lower nest secured thereto, respectively, but no structure is provided for their engagement. With such a construction, while the umbrella is in use, the inner shaft and the outer shaft readily turn or displace relative to each other and under the action of an external force or due to abnormal handling of the umbrella by its user, but it does not matter usually. In the case of opening or closing the umbrella, however, there is a fear that its ribs are easily twisted, causing trouble in the opening or closing of the umbrella. Moreover, in the prior art examples the spring is directly put on the top end portion of the inner shaft above the upper nest. When the umbrella is opened and closed, any friction between the spring and the outside of the top end portion of the inner shaft is always caused by the expansion and contraction of the spring. Since the both are made of metal alone, their friction is very likely to make a harsh grating noise. Besides, their surfaces are liable to damage by their long-term friction, and since the user usually stands the umbrella with the ferrule downward, there is a fear that rain water flows between the inner shaft and the spring and causes the top end portion of the inner shaft and the inside of the spring to corrode, shortening the service life of the umbrella in its entirety.
In the prior art examples, the inner shaft has a stopper provided thereon at an appropriate position and as the umbrella is opened, the outer shaft slides on the inner shaft to a predetermined position where the lower nest strikes against the stopper when the umbrella is fully opened. The stopper serves as a positioning means, but in practice, an appreciably severe shock is given to the umbrella whenever the lower nest bumps against the stopper. This is not comfortable to the user. If the user does not firmly hold the handle, the user may let go of the umbrella in spite of oneself. This is considerably dangerous.